The present invention relates to a tool chuck, and more particularly relates to an improvement in construction of a chuck for firmly holding a tool such as a drill bit or a driver bit of electric work devices. This invention relates to a chuck for use with rotating equipment such as drills. Such rotating equipment is commonly driven manually or in the case of power drivers, electrically, hydraulically or pneumatically. More particularly, the present invention relates to a style of chuck which may be keylessly tightened or loosened by hand, or can alternatively, be tightened or loosened by rotation of a twist key which can be engaged by partial extraction from within a key recess about the periphery of the chuck body. The mechanical gearing is located within the interstitial void of the chuck body and through a series of gear reductions, offers mechanical advantage to increase the torque that is applied to the jaws in the tightening and loosening process.
Both hand and powered tool drivers are well known. The general configuration is a rear rotational driver, mechanically coupled to a chuck by threaded engagement or via a tapered sleeve that mates into a corresponding recess in the chuck body. The chuck has any number of circumferentially equally spaced jaws that are advanced concurrently both axially outward and radially inward from a front orifice. It is the advancement of these jaws that grip a tool or bit. The chuck may be used to hold any one of a multitude of tools such as screw or nut drivers and cutting, shaping or grinding bits, although the most common is a twist drill. With such a diverse selection of tool bits, the diameters and configurations of the shanks vary considerably from circular to polygonal in cross section. For this reason the chuck is adjustable over a relatively wide range.
Numerous chucks have been developed and are well known in the art. The most common type is found on the household hand drill. This is perhaps the most simple configuration with three jaws approximately spaced circumferentially 120 degrees apart from each other. Each jaw is housed in an angularly disposed passageway in the chuck body configured so that rotation of the chuck body in one direction with respect to a constrained nut engaging the jaws forces the jaws into gripping relationship with the tool bit. Counter rotation acts to release the gripping relationship. The rotation is commonly accomplished through the use of a key. If sufficient torque can be developed by hand rotation of the chuck, i.e. enough torque to hold the tool bit such that the rotating tool may be used without the disengagement or loosening of the tool bit from the jaws of the chuck, a key is not necessary. This is known as a “keyless” chuck, and the act of securing a tool bit in this manner is known as “keyless” operation. This is a desirable configuration in that bits can be quickly removed or inserted and lost or damaged keys do not hinder the process.
In the current state of the art, key and keyless chucks both have several disadvantages. First, if they require a key, it is made of a specific size as all keys are not interchangeable. Keys are easily lost and the engagement teeth can become stripped. Replacement keys can often be hard to find. Second, this type of tightening is slow as it requires insertion and separate tightening at different axial positions around the chuck. If it is a keyless chuck it often does not hold the tool bit secure enough for arduous operations, or conversely it holds the tool bit too firm such that hand release of the bit is extremely difficult. The disadvantages of the keyed and keyless chucks are in direct opposition to their respective advantages. It would be desirable to have a style of keyless chuck that offers additional torque to secure or release the tool bit. It would also be advantageous to have a style of chuck that has a key that can't be lost or that does not slip off of the outer, planar tightening ring gear because of minimal teeth engagement.
The present invention resolves all of these drawbacks in the existing chucks and just as importantly, has cleaner aesthetics. By housing the planar tightening ring gear and tightening mechanism inside the chuck's nose cone, these gears can be lubricated with oil or grease without fear of spreading it onto the user, and the gears are protected from chipping. By utilizing a second planar gear in the tail section of the chuck that can be brought into use to increase the torque, the present invention offers significant increases in user friendliness.